lighting tip sheet (v-2.0 march 2011)

8/17/2019 Lighting Tip Sheet (v-2.0 March 2011)

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Lighting is a major energy consumer in commercial buildings. Heat generated from electrical lighting also contributes signicantly to the energy needed for

cooling of buildings. ECBC prescribes the amount of power for lighting, species

types of lighting controls, and denes situations where daylighting must be used.

This document (primarily adapted from E Source Technology Atlas - Lighting

and Energy Eciency Manual) provides guidance towards the design of ECBC

compliant lighting systems in commercial buildings.

ENERGY CONSERVATION

BUILDING CODE TIP SHEET

Version 2.0- March 2011

BUILDING LIGHTING DESIGN

Credits:

E Source echnology Atlas Series - Lighting

Energy Efficiency Manual - Donald R. Wulfinghoff

All iance to Save Energy

USAID ECO-III Project

International Resources Group

Phone: +91-11-4597-4597

Fax: +91-11-2685-3114

Email: [email protected]

In commercial buildings,

lighting typically accounts or 20-40% o total energy consumption.

Lighting is an area that oers manyenergy eiciency opportunities in almostany building, existing as well as new. Atypical commercial building has manylighting requirements and each normallyhas its own set o options or improvinglighting eiciency.

Centuries ago, a person could read by

the light of a single candle but today aperson in a typical office uses hundredsor even thousand times more light. Over

1

the years, illumination standards haveincreased radically along with efficiencyof lamps (Fig. 1). Modern offices requi rebetter illumination, specific activity-oriented lighting provisions, and goodvisual quality to maximize productivity.

People want light for different reasons,and a good lighting designer must keepthem in mind. Different tasks requiredifferent amounts and types of light. Forexample, a surgeon needs lots of light with

low glare and excellent color rendering;restaurant owners and diners often wantlow light levels, warm tones, and a feeling

of intimacy; corporate boardrooms callfor lighting that reinforces a feeling ofimportance and success while adapting toaudio-visual presentations; retail outletsin many situations want to make theirmerchandise sparkle so that it draws thecustomers and encourages them to buy.

An office worker needs modest ambientlighting level, good task lighting on worksurface, and minimal glare to effectivelyread and work on computers. Tus the

quality of light in majority of situationsis as important as the quantity of light. While energy efficiency is an

attractive goal for many reasons,lighting designers must also considera host of other factors, including theeffect of quality of light on the visualcomfort and health of the occupants.Small improvement in lighting qualitycan improve productivity of the usersubstantially.

he right quality and quantityof light can be provided efficiently

(with less energy) by using the righttechnology and its effective integration

with dayl ight.

12 lm/80 W

0.15 lm/W

7.5-hour life

730 lm/13 W

56 lm/W

10,000-hour life

Notes: lm = lumen; W = watt.

730 lm/60 W

12 lm/W

1,000-hour life

180 lm/60 W

3.0 lm/W

50- to 100-hour life

CandleC o m p a c t

fluorescent Tungs ten -fi lame nt

incandescent

Carbon-filament

incandescent

Fig 1: Evolution of Lighting Technologies

(Source: E Source Lighting Atlas)

CompactFlourescent

Version 2.0- March 2011 ECBC Tip Sheet > Lighting 1


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Daylighting Sunlight is free and uses no electricity.Human beings by nature are accustomed tolive and work more comfortably in sunlight.

Although our optical sensors (humaneye) can only see a very narrow portion ofelectromagnetic spectrum, they are welladapted to sunlight (Fig. 2). Both economics

and the imperatives of health and aestheticsfavour the practical use of daylight in thebuildings. Simply adding a large numberof windows to a building to “let the sunshine in” can create excessive glare, makeother spaces look dark by contrast, andadmit so much unwanted heat gain due tonear infrared radiation that the space couldbecome virtually unusable.

Poorly designed daylit areas can be worsethan spaces with no daylight. Whendone properly, daylighting coupled

with energy-ef ficient glazing and good

lighting controls can make new andexisting buildings efficient, delightfuland healthy. he tools to do it rightexist, and are being applied by a growingbody of talented lighting designers.

Heating Effects of Lighting

Lamps use electricity to produce light.Except for a small percent of energy usedin producing light, majority of energy usedby interior lights ends up as heat inside thebuilding. In most commercial buildings,

lighting is one of the largest sources ofinternal heat gain. Other sources of internalheat gains are people and equipment inbuilding. Compared to typical lighting,energy-efficient lighting adds less heatto space per unit of light output. Eachkilowatt-hour (kWh) reduction in lightingenergy saves 0.4 kWh in cooling energy.

Lighting Technology

Lighting is one of the fastest developingenergy-efficient technologies: energy-efficient 8 and 5 linear fluorescent

lamps, linear and compact fluorescentdimming systems, long-life electrode lessf luorescent lamp systems, white LEDs,and PV powered DC lighting systems.

Fig 2: Solar Spectrum


300 500 700 900 1,100 1,300 1,500 1,700 1,900

Near- infared

(52%)

Visible(45%)

UV(3%)

R e l a t i v e I n t e n s

i t y

Wavelength

(nanometers)

Spectral distribution of

Solar radiation

Eye Sensitivity

Curve

into account several human factors inspecifying lighting systems.

Lighting Design Tools

Lighting software helps designers tocompare lighting alternatives and makessure that the ultimate design choice

wi ll provide qua lity light. Demands

on lighting designs are becomingmore complex as both lighting qualityand energy efficiency have becomehigh priorities. In addition, a widerange of variables—different lightsources, fixtures of varying efficiencyand photometric, and rooms with a

wide range of geometries and sur facefinishes—all make lighting design achal lenge worthy of computer modeling.In particular, the trend among fixturemanufacturers to use specular reflectorsthat send light in particular directionsmakes modeling more useful than it was

with the old-sty le, white-painted diffusereflectors. Most computer models canalso simulate the effects of daylight andcan be used to help designers to developeffective control strategy for getting theoptimum blend of electric lighting anddaylighting.

Once constructed, a computer lightingmodel can be easily modified so that variousfixture designs and spacings can be evaluatedand compared in terms of horizontal and

vertical light levels. Designs that give properquality and quantity of lighting can beevaluated for their energy consumption,and the design that gives both the desiredlighting level and the lowest life-cycle costcan be selected. Output from lightingsoftware can also be input into software thatmodels an entire building to enable analysisof the impacts of lighting decisions on otherbuilding systems. Lighting professionals whodo not first model the design, face the risk ofgetting poor light distribution or more light

than they expect. Both the problems can bedifficult and expensive to correct.

Lamp Technologies

Incandescent Lamps An incandescent lamp consist s of atungsten wire filament that glows andproduces visible light when heated to ahigh temperature. Unfortunately, 90to 95 % of the power consumed by thehot filament is emitted as infrared (heat)radiation. Although inefficient from

an energy standpoint, the luminousfilament can be made quite small, thusoffering excellent opportunities forbeam control in a very small package.

Selection of lamp should be thestarting point when deciding how toilluminate a space efficiently. Lampsare also the primary actor in lightingefficiency, and they determine boththe electrical and color characteristicsof the lighting systems. When a lampis coupled with its auxiliary equipment

(e.g. a ballast or “choke”) and installedin a luminaire (fixture), it becomes thecomplete light source that is the basicelement of the lighting design.

It has long been recognized that anincandescent lamp is much less efficientthan fluorescent and High IntensityDischarge (HID) lamp, and that it hassmaller operating life. In recent years,further improvements in the efficiencyand color characteristics of fluorescentand HID lighting have increased theiradvantage over incandescent lighting.

Light Distribution

hough energy-efficient technologiescan cut down energy consumption andoperating costs, the light path originatingfrom the light source if not properlydirected and distributed to the task oractivity area through appropriate lampluminaires (fixtures), could adverselyaffect the quality of light and reduceenergy efficiency gains. Consequently,luminaire selection and design should

go together with any energy-efficientlighting strategy.

Lighting Controls

Controls are the last step in the energy-efficient lighting design process andshould be designed after high-efficiencylight sources have been chosen. hecontrollability of light sources varies

widely, with low-efficacy incandescentlamps being the easiest to control.echnological developments continue

to provide new control capabilities forfluorescent and HID systems.

Efficient Lighting Design

Optimal lighting solutions can only bereached by considering the integrationof daylight, lamps, fixtures, controls,building configurations, interiorfurnishing, etc. Ideal lighting providesthe appropriate level of illuminationfor the activity with minimum inputof energy, with required visual quality.For efficient lighting design, it is often

necessary to involve a skilled lightingdesigner who combines energy eff iciency

with good quantit y and qua lity of lightneeded for the activity and also takes



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For implementing the ECBC provisionsin lighting system, it is important tounderstand the ollowing technical terms:

Astronomical time switch: An automatictime switch that makes an adjustment or

the length o the day as it varies over the year.

Ballast: All fluorescent lamps need aballast to operate. Te primary unctionso a ballast are to provide cathode heating where necessar y, initiate the lamp arc with high-voltage, provide lamp operating power, and then stabil ize the arc bylimiting the electrical current to the lamp.Secondary unctions include input power-quality correction and control eaturessuch as lamp dimming or compensationor lumen depreciation.

Candela: It is a measure o the intensity(or brightness) o light source in a givendirection (Fig. 3).

Color Rendering Index (CRI): Measuredon a scale o 0 to 100. It specifies the colorrendition properties o a lamp. Te higherthe average CRI value, the better the lightsource. A cool white fluorescent lamp has aCRI o 62 to 70, 8 lamps range rom 75to 98 and standard high-pressure sodiumlamps have CRIs o about 27. Lamps withCRIs above 70 are typically used in officeand living environments.

Correlated Color Temperature (CCT):

A measurement on the Kelvin (K) scalethat indicates the warmth or coolness oa lamp’s color appearance. Te higher the

color temperature, the cooler or bluer thelight. ypically, a CC rating below 3200K is considered warm, while a rating above4000 K is considered cool.

Illuminance: Te amount o light that

reaches a surace. It is measured in ootcandles (lumens/f2) or lux (lumens/m2).

Installed interior lighting power: Te power in watts o all installed general,task, and urniture lighting systems andluminaires.

Lighting Power Allowance:

a) Interior lighting power allowance: themaximum lighting power in wattsallowed or the interior o a building

b) Exterior lighting power allowance:the maximum l ighting power in wattsallowed or the exterior o a building

Lighting Power Density (LPD): Telighting power drawn per unit o areao a building type or space. It is usuallyexpressed as watts per square meter or watts per square oot.

Occupancy Sensor: A device that detects

the presence or absence o people withinan area and causes lighting, equipment, orappliances to regulate their operation orunction accordingly.

Reflectance: Te ratio o the light reflectedby a surace to the light incident upon it.

Visible Light Transmittance: Also knowas the Visible ransmittance, is an optical property o a light transmitting material(e.g. window glazing, translucent sheet,

etc.) that indicates the amount o visiblelight transmitted o the total incidentlight.

Luminance: It measures the brightnesso a source when viewed rom a particulardirection. It is expressed in term ocandela/m2 o the light emitting surace.Luminance describes the intensity olight that is leaving a surace whereasilluminance describes the intensity olight that is alling on a surace. For lightreflected rom a surace, luminance equals

illuminance multiplied the reflectance othe surace.

Lumen: It is the unit i total light outputrom a light source o a lamp is surroundedby a transparent bubble; total light flowthrough the bubble is measured in lumens.Lamps are rated in lumens, which is thetotal amount o light they emit, not their

brightness and not the light level on asurace. ypical indoor lamps have lightoutput ranging rom 50 to 10,000 lumens.Lumen value is used or purchasing andcomparing lamps and their outputs.Lumen output o a lamp is not related tothe light distribution pattern o lamp.

Lux: It is the unit o illuminance andindicates the density o light that allson a surace. One lux equals one lumen per square meter o the surace while onelumen per square oot o the surace isequal to 1 oot-candle. One oot-candleequals 10.76 lux. Average indoor lightingrange rom 100 to 10,000 lux and averageoutdoor sunlight is almost 50,000 lux.Tese lumens and candela are measuredby special photometric instruments inlaboratories and are used primarily orcomparing light sources independento site conditions. Lux and oot-candlesare measured in the field with a meterand may be dependent on site conditionsbecause, unlike candelas or lumens, they

are influenced by fixture, room suracereflectance, partitions, and other actors.

Lamp Efficacy: Lamp Efficacy is ameasure o the output o a lamp in lumens,divided by the power drawn by the lamp.Its units are lumens per watt. Lampefficacy values are based exclusively on thelamp’s perormance and do not includeballast losses. Lamp system efficacy valuesmeasures the perormance o the lamp andballast combination and this includes the

ballast losses.

Light Luminaire (Fixture): A lightfixture, consists o the ballast, lamp,reflector, in some cases a lens, designed todistribute the light, position and protectthe lamps, and connect the lamps to the power supply.

T#: As in 5, 8, 12 fluorescent lamps. stands or tubular; the number describeslamp diameter in one-eighth-inchincrements. A 8 lamp is eight-eights o

an inch (or 1 inch) in diameter; a 12 istwelve-eighths o an inch (or 1.5 inches) indiameter.

A 1-candlepower light source delivers a luminous intensity of

1 candela (cd) in all directions. Assuming that the sphere has

a radius of 1 foot (ft), the light source will deliver 1 lumen (lm)

of light to each square foot (ft2) of surface of the sphere, so the

illuminance is 1 foot-candle (fc).

1cd

1cd

1-ft2”hole”

R a d i u

s = 1 f t

Illuminance

At any point onthis imaginary 1-ft-

radius sphere, the

illuminance equals

1 lm/ft2, or 1 fc.

Luminous

intensity = 1 cd

One candle power

luminous source

Light flow=1lm/ft2

Fig 3: Relationship of light measurement

terms


Key Technical Terms



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are shown in able 1. Electronic ballasts, which have come to dominate the marketfor compact fluorescent lamps (CFLs), aremore efficient, weigh less, and are quieterthan magnetic ballasts.

Some argue that CFLs are such smallloads that their PF and HD should notbe o major concern, especially becausemany other end-use devices on the powergrid—personal computers, copiers, laser printers , microwave ovens , televisions,stereos, variable-speed motor controls,and others—also degrade power qualityin varying degrees and typically use armore power per unit.

Mercury is an essential ingredient formost energy-efficient lamps. Te amountof mercury in a CFL’s glass tubing is small,about 4mg. However, every lamp productcontaining mercury should be handled

with care. Fig. 6 puts mercury pollution

Linear and Compact FluorescentLamps (CFLs)he basic fluorescent lamp contains lowpressure mercury vapor and inert gasesin a partially evacuated glass tube thatare lined with phosphors (Fig. 4). CFLsoperate in the same manner as linearfluorescent lamps. he high surface

brightness of CFLs requires the use ofrobust rare earth phosphors, such asthose used in modern 8 and 5 linearfluorescent lamps, in order to provideacceptable lumen maintenance.

he efficacy (lumens per watt) offluorescent lamps varies considerably

with lamp wattage and ballast typeand quality (Fig. 5). he efficacy of a5-watt CFL on a low-quality magneticballast, for example, can be as low as27 lumens per watt (lm/W). At the

other extreme, two 36-watt compactf luorescent lamps powered by a singlehigh-quality electronic ballast delivernearly 77 lm/W. ypical incandescentlamps operate with an efficacy of 15 to18 lm/W, so even a low-efficacy CFLis significantly more efficient than theincandescent lamp it might replace.

CFLs have been substituted or anincandescent lamp using the rule othumb that a CFL uses only 20-25% power to deliver the same lig ht output.

However, but many manuacturers’ product literat ure exaggerates CFLperformance by “rounding up” whenidentifying the “equivalent” incandescentlamp. For example, a CFL may beadvertised as a replacement for a 75-watt,1,200-lm incandescent lamp, but it mayonly produce 1,000 lm. A more accuratedescription would put the light output ofa CFL midway between that of 60W and75W incandescent lamps.

Te effect of CFL on power quality hasbeen debated widely for several years. Te

two primary issues are the Power Factor(PF) and otal Harmonic Distortion(HD) of the ballasts. ypical PF andHD ranges for various ballast types

Notes: Hg = mercury; UV = ultraviolet

UV photon

Hg

Visible photon

Fluorescent lamps maintain an electric arc th roughgas, in contrast to the continuous metal ilamentsused in incandescent lamps.

Fig 4: Fluorescent lamp operation


from the use of CFLs in a broader context(mercury pollution from thermal powerplants generating power). High Intensity Discharge LampsHID lighting sources are the primaryalternative to high-wattage incandescentlamps wherever an intense, concentratedsource of light is required. here arethree basic types of HID lamps: MercuryVapor, Metal Hal ide, and High-PressureSodium. Although HID lamps canprovide high efficacy, they have specialrequirements for start-up time, restriketime, safety, and mounting position.

a) Mercury-Vapor LampsMercury-vapor (MV) lamps use a high-pressure mercury discharge that directlygenerates visible light (Fig. 7). Someversions also use a phosphor coating on

Table 1: Magnetic and Electronic Ballasts Characteristics for

CFLs

Ballast Characteristics Magnetic Electronic

CFL base compatibility Mostly two-pin Mostly four-pin

Lamp/ballast efficacy Low High

Weight High Low

Noise level Slight 120-Hz hum Very quiet

Cost Cheaper Expensive

No. of lamps powered/ballast 1 or 2 1, 2, 3 or 4

Dimmability No Available

Universal input voltage No Available

Power Factor 0.4 to 0.7 (normal; > 0.9 (better)0.4 to 0.7 (normal; > 0.9 (better)

otal Harmonic Distortion (%) 6-18 (normal); 15-27 (better) 75-200 (normal); 16-42 (better)

Source: E Source Lighting Atlas

Fig 5: Relative efficacy of major light sources


Standard incandescent

Tungsten halogen

Halogen infrared reflecting

Mercury vapor

Compact fluorescent 5–120 W

Low-pressure sodium

Efficacy, including ballasts

(lumens per watt)

Fluorescent (Linear and U-tube)

Metal halide

High-pressure sodium

0 20 40 60 80 100 120 140



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the inside of the outer bulb to convertthe small amount of ultraviolet (UV)light generated by the discharge intoadditional visible light that improves thecolor of the lamp. MV lamps have lowerefficacy than fluorescent lamps and otherHID lamps.

b) Metal-Halide LampsMetal-Halide (MH) lamps are similarto MV lamps but feature an importantimprovement: the addition of iodides ofmetals such as thallium, indium, andsodium to the arc tube. hese metalsproduce a higher quality and quantityof light than mercury, and the halidesform the basis of a regenerative cyclethat prevents the metal s from depositing

on the wall of the arc tube. MH lampstake three to five minutes to reach fulloutput. Restarting after a shutdown orpower interruption may require as much

its proponents. LEDs use solid-stateelectronics to create light. Majorelements in the packaging of an LEDinclude a heat sink to dissipate theenergy that is not converted into light, alens to direct the light output, and leadsto connect the LED to a circuit. Fig. 8shows a cross section of an LED fixture.

LEDs are increasing in efficacy, lightoutput, and color availability whiledropping in cost. High brightness,narrow-band, or various-color LEDsare being used increasingly in vehiclesignal lights, traffic signal lights, exitsigns, and decorative and informationdisplay applications. Composite units ofred, green, and blue LEDs, or of systemscomposed of a blue or violet LED plusa phosphor coating, are being used tocreate white light further expanding LEDapplications.

able 2 shows the comparativecharacteristics of different light sources.

Fixture & Reflector he full potential for energy-efficientlighting comes only through intelligentintegration of many system variables.hese range from the most minutedetails of lamp design through theblending of lamps, ballasts, reflectors,lenses, and other components.

It is not enough to select good lamps

and other components. However,one must also understand how thesecomponents behave in the field. In thelab, fluorescent lamps are typically ratedin open-air fixtures at 25°C ambienttemperature with a reference ballast thatdrives the lamp to its fu ll rated output. Inthe field, however, many ballasts underdrive or overdrive lamps. Te so-calledballast factor and the temperature of thelamps in field conditions can cause lightoutput to vary by 20 percent or more.Lamp position—whether it is installed

base up or base down—can also have a10 to 20 percent effect on light outputfrom certain sources, such as compactfluorescent lamps.

Fig 8: LED Operation


Plastic lens

Silicone

encapsulate

InGaN

Semiconductor

Flip chip

Solder connection

Silicon submount chip with

ESD protectionHeatsink slug

Gold wire

Cathode lead

as 10 to 15 minutes for the arc tube tocool and the mercury and metal-halidegas densities to drop before the arc canbe restruck, plus another three to fiveminutes to reach full output again. MHlamps produce relatively high levels ofUV radiation that can be controlled withshielding glass in the lamp or fixture.

c) Sodium LampsIn sodium lamps, a high-frequency,high voltage pulse ionizes a rare gas,typically xenon, in an enclosed tube.he ionized gas in turn vaporizes asodium-mercury amalgam. An electric

arc through this vapor excites sodiumatoms, which emit visible light—mostlyin the longer wavelengths betweenyellow and red—when they return totheir ground state. For high-pressurelamps, the gas mixture is sealed in atranslucent polycrystalline aluminacylinder that transmits 90 percent of thevisible light created inside it. Sodiumlamps vary widely in their efficacy andcolor quality, and their performance isvery sensitive to the gas pressure inside

the arc cylinder. Improving the qualityof light from some sodium sources,significantly reduces their efficacy.

Light-Emitting DiodesDuring the past few years, solid-statelighting in general and Light EmittingDiodes (LEDs) in particular havereceived more attention than any otherlighting technology. his high level ofinterest is based on the demonstratedperformance advantages of LEDs inmany niche applications, and it is also

fueled by LEDs’ potential for substantialenergy savings in general lightingapplications if the technology can meetthe performance targets established by

Fig 7: Mercury Vapor Lamp Schematic


Starting electrode

(probe)

Starting resistor

Trimetallic operating

electrode

Phosphor coating

Quartz arc tube

Visible light

2

2

33 Outer bulb

1

1 UV light

Electric

field

Electrode

Electron Mercury

atom

Quartz arc tube

As energy-efficient lighting becomesmore popular, it is important that thelamp products are disposed o in a saeand responsible way. Mercury is releasedinto environment when products with mercur y are broken, disposed oimproperly, or i ncinerated.

In spite of the sensational reporting inprint and electronic media, the fact is thatCFLs present an opportunity to preventmercury contamination of air, where itmost affects the health. One of the majorsources of mercury in air comes fromburning fossil fuels such as coal, the mostcommon fuel used in India to produceelectricity. A CFL uses 75% less energy

than an incandescent light bulb and lastssix times longer. A thermal power plantemits 10 mg of mercury to produce theelectricity to run an incandescent bulbcompared to only 2.4 mg of mercury torun a CFL for the same time.

Fig 6: Mercury Emissions by Light

Source Over Year Life

(Source: US EPA, June 2002)

12

10

8

6

4

2

0

Emissionsfrom coal

power point

IncandescentCFL

Emissions from coalpower plant

2.4

10.0

4.0 Mercury usedin CFL

M i l i g r a m s o f M e r c u r y

Environmental Impacts of Mercury Used in Fluorescent Lamps



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Table 2: Comparative Characteristics of Different Light Sources (Source: Energy Efficiency Manual)

CharacteristicsConventional

Incandescent

Halogen

Incandescent

Fluorescent

Tube Light Compact Fluorescentt

Lumen Output(lumens) 10 to 50,000

300 to 40,000 900 to 12,000 250 to 1,800

Lumen Degradation(% of initial lumens) 15 to 40 8 to 15 8 to 25 15 to 20

Service Life (hours) 750 to 4,000 2,000 to 6,000 7,000 to 20,000 10,000

Efficacy (lumensper watt)

7 to 22 14 to 22 30 to 90 25 to 70, Including ballast losses

Ballast EnergyConsumption (percentof lamp wattage)

None None5 (high quality electronicballasts) to 20 (cheapmagnetic ballasts)

10 (electronic ballasts) to20 (magnetic ballasts)

Potential for LampSubstitution andMismatch

Unlimited substitution wherever the lamp fits thefixture, provided that fixtureheat capacity is adequate.

Unlimited substitution wherever the lamp fitsthe fixture, providedthat fixture heatcapacity is adequate.

Limited within narrow rangesof wattage by lamp size, socketstyle, and ballast compatibility.

Screw-in lamps substitute for eachother and for most incandescentlamps, except where they aretoo large to fit. Cannot be usedin dimming fixtures. Othercompact lamps have specializedbases that limit substitution.

Color RenderingIndex (CRI)

100 100 50 to 95 60 to 85

Effect of emperatureon Light Output

Minimal. Minimal.

Serious loss of light

output above and belowoptimum lamp temperature(about 38°C).

Serious loss of Eight output above andbelow optimum lamp temperature(about 38°C). Lamps that use mercuryamalgam maintain light outputmuch better at low temperatures.

Starting Interval Instantaneous. Instantaneous.

Instantaneous for lamps withInstant-start ballasts. Aboutone second for rapid-startballasts. One to severalseconds for preheat ballasts.

One to several seconds. Units withmercury amalgam require about oneminute to reach full brightness.

Control of LightDistribution

Some styles allow verytight focussing.

Some styles allow verytight focussing.

Allows only loosefocussing. Most controlperpendicular to lamp axis.

Allows moderately tightfocussing, especially withunconventionally large fixtures.

Acoustical Noise Minimal. Minimal.

All magnetic ballasts producesome noise, and defectivenoisy units are fairly common.Some electronic ballastshave noticeable noise.

Good units are quiet, cheapunits may be noisy.

Power Factor No problem. No problem.Ballasts with high power factorare available. Some ballastshave low power factor.

Units with high power factor areavailable. Some have low power factor.

Harmonic Distortion None. None.

High distortion occurs

primarily In cheaperelectronic ballasts.

All units with electronic ballasts

have significant harmonicdistortion. Cheaper units havemuch more than others.



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Mercury

Vapor

Metal

Halide

High-Pressure

Sodium

Low-Pressure

Sodium

0 to 60,000 4,000 to 160,000 2,000 to 50,000 1,800 to 35,000

o 45 30 to 45 25 to 35

00 5,000 to 20,000 10,000 to 24,000 18,000

o 65 70 to 130 50 to 150 100 to 190

rge lamps) to 50 (small lamps) 7 (large lamps) to 30 (small lamps) 10 (large lamps) to 35 (small lamps) ca. 20

titutions within type highly limitedallast compatibility. Some mercuryr lamps substitute for incandescent

ps without external ballasts, but theseminimal efficacy advantage.

Substitutions within type highlylimited by ballast compatibility.

Substitutions within type highly limited byballast compatibility. Some HPS lamps aredesigned as direct substitutes for mercury vaporlamps, offering major efficacy improvement but worse color rendering than other HPS lamps.

Substitutions withintype highly limited byballast compatibilityand specialized sockets.

o 50 60 to 70 20 to 85 0 to 20

imal loss of output above -29°C. Minimal loss of output above -29°C. Minimal loss of output above -29°C. Minimal loss ofoutput above -29°C.

8 minutes 3 to 10 minutes 5 to 10 minutes 7 to 15 minutes

ws moderately tight focussing. Allows moderately tight focussing. Allows moderately tight focussing.

Allows only loosefocussing. Mostcontrol perpendicularto lamp axis.

asts are magnetic, andduce some noise.

Ballasts are magnetic, andproduce some noise.

Ballasts are magnetic, and produce some noise.Ballasts are magnetic,and producesome noise.

asts with high power factor are available.e ballasts have low power factor.

Ballasts with high power factorare available. Some ballastshave low power factor.

Ballasts with-high power factor are available.Some ballasts have low power factor.

Ballasts with highpower factor areavailable. Some ballastshave low power factor.

or, assuming that thests are magnetic. Minor, assuming that theballasts are magnetic. Minor, assuming that the ballasts are magnetic.

Minor, assuming

that the ballastsare magnetic.



8/12

Maximum lighting power requirementsare also included for exit signs andexterior building grounds lighting[ECBC 7.2.2 and 7.2.3]. As per ECBC, for Exterior Grounds

Lighting luminaires greater than 100 Watts shall have a minimum efficacy of60 Lumens/Watt, unless controlled with

a motion sensor. As shown in Fig. 9,luminaires meeting these requirementsinclude fluorescent, mercury vapor andhigh pressure sodium.

Prescriptive RequirementsFor meeting Interior Lighting Powerrequirements, [ECBC 7.3], the installedinterior lighting power is first calculatedtaking into account all the luminairesincluding lamps, ballasts, currentregulators, and control devices proposed tobe installed in the building. Compliancecan then be achieved by the Building

Area Method [ECBC 7.3.2] or the SpaceFunction Method [ECBC 7.3.3]. Boththe methods compare installed lightingpower (Watts) as proposed in the building

with maximum allowed lighting powerallowance (Watts) calculated based on thevalues of Lighting Power Densities (LPDin W/m2) given in able 7.1 and able 7.2of ECBC respectively. Sample LPD valuesare given in able 3.

Building Area Method For easier understanding consider theproposed building is an exclusive one‘building area type’ (such as office).

Step 1: Depending upon the typeof the proposed building, select thecorresponding permissible LPD fromable 7.1 of ECBC.

Step 2: Determine the gross lightedfloor area of the building.

Step 3: Calculate the interior lightingpower allowance (LPA) which is theproduct of the gross lighted floor area

ECBC Compliant Lighting

Design Strategy

Many things can go wrong with thebuilding lighting system and well-intentioned attempts to make it energyefficient. Critical missteps to watch outfor include:

• Specifying the amount of light forgeneral usage without considering theneeds of specific tasks (for example,supplying light for general office workbut not addressing the effect of glareon computer screens);

• Designing a daylighting strategy butnot enabling the lighting system todim or turn off when there is sufficientdaylight in the interior space;

• Supplying inadequate control oflighting by not allowing lights to beadjusted to specific needs (i.e. turnedon in groups or “banks”, or dimmed),and not providing easily accessiblecontrol switches;

• Adding a large window area to thefaçade for daylighting but ignoringthe problems of solar heat gain and theneed for shading;

• Designing/sizing the building’s HVACsystem on rules of thumb and notaccounting for the reduction in coolingloads created through efficient lighting

system.

Compliance Approaches - GeneralECBC sets mandatory and prescriptiverequirements for lighting power densityand lighting controls. Compliance withprescriptive requirements can be shownthrough the Building Area Method orthe Space Function Method. In bothcases, mandatory lighting requirementsare still applicable.

Mandatory RequirementsLighting Control—Astronomical imersand occupancy sensors are required toautomatically turn lights off in mostenclosed interior spaces [ECBC 7.2.1.1].Control devices also required to override anautomatic shutoff control (either manuallyor through an occupancy sensor) [ECBC7.2.1.2]. If Daylighting strategy is used inthe design, ECBC requires controls that canreduce the light output of luminaires in thedaylit space, by at least half [ECBC 7.2.1.3].

Tere are also control requirements

for exterior lighting (with photosensoror time switches) and specialty lightingapplications (i.e. displays, hotel rooms, tasklighting) [ECBC 7.2.1.4 and 7.2.1.5].

and the selected LPD for the building.(Gross Lighted Floor Area X LPD)

Step 4: Calculate the total installedlighting power (ILP) of the all proposedluminaires in the building (in accordance

with ECBC 7.3.4.1)

Step 5: Compare ILP values with LPAvalues. If ILP is less than or equal toLPA, the lighting system of the buildingcomplies with ECBC. Otherwise, it isnot.

Space Function Method

Step 1: Looking into the listed spacefunction heads/sub-heads given inthe able 7.2, identify various spacefunct ions (enclosed by partitions 80% orgreater than ceiling height) as applicablein the proposed building (for instance,hospital building which has number ofsub-heads), and also determine theircorresponding LPDs f rom the able.

Step 2: Determine the gross lightedfloor area of each of the identified spacefunction heads/sub-heads (as guided inECBC under 7.3.3 b).

Step 3: Calculate the interior lightingpower allowance (LPA) which is the sum

of the product of the gross lighted floorarea under each of space function head/sub-head and the corresponding LPD ofeach.

Step 4: Calculate the total installedlighting power (ILP) of the all theproposed luminaires in the building (inaccordance with ECBC 7.3.4.1).

Step 5: Compare ILP values with LPAvalues. If ILP is less than or equal to

LPA, the lighting system of the buildingcomplies with ECBC. Otherwise, it isnot.

Table 3: Sample LPD Values (max. permissible) as per ECBC

Building Area

Method

LPD

(Watts/m2)

Space Function

Method

LPD

(Watts/m2)

Office 10.8 Office Enclosed/Open Plan 11.8

Library 14.0 Classroom/Lecture/ raining 15.1

Retail/Mall 16.1 Family Dinning 22.6

Cafeteria/ Fast Food 15.1 Hospital (Emergency) 29.1

Parking Garage 3.2 Corridor/ransition 5.4



9/12

o complete the zonal cavity calcu lation,three fundamental quantities must beknown: the Room Cavity Ratio (RCR),the Coeff icient of Utilizat ion (CU), andthe Light Loss Factors (LLF).

Room Cavity Ratio: Room Cavity Ratio(RCR) characterizes a room by shapeand is calculated using the formulabelow, using the room dimensions andlight fixture distance over the working

desk. Refer Figure 10, as an examplefor sample calculation of RCR as shownbelow:

Coefficient of Utilization: CU is ameasure of the fixture’s ability to distributelight down to the work plane using the RCR

4.55(10-2.5-1.5) (2 0+10)= = 20 X 10

5(H) (L+W)

L X W =RCR

Exterior Lighting Power requirements[ECBC 7.3.5] require calculating theconnected lighting power for buildingentrances, exits, and facades. hesemust be below the power limits listedin ECBC for each lighting application.Figure 9 suggests specific technologiesfor exterior ground lighting.

Basic Light Design Concept

When designing or retrofitting the

lighting, the general illuminance, oramount of light that reaches a surface, canbe assessed through manual ca lculations.Te Illuminating Engineering Society ofNorth America (IESNA) has establisheda procedure for determining how muchilluminance is needed for a given task. Te

Zonal Cavity or Lumen Method (Source:E Source echnology Series-LightingVol. I) described below considers severalfactors to determine type and numberof fixtures that would be appropriate to

meet the illuminance requirements ofthe space.

Zonal Cavity Method: he basicformula used in this method springfrom the definition of illuminance: 1foot-candle (fc) = 1 lm/ft2. hat is, tomaintain an average of 40 fc in an areaof 100 ft2, one needs 40 x 100 = 4,000 lmcoming out of the fixtures. But severalmodifying factors must be considered:he fixture is not absolutely efficientin dispensing light; much of that light

may be lost while being reflected off ofvarious surfaces before it arrives at the

work surface. A lso, l ight source s degrade with age and dir t buildup.

value and the surface reflectance of the walls, floor, and ceiling. Fixture efficiencyis the proportion of lamp light that escapesthe fixture at any angle, whereas CU isthe proportion of lamp light that reachesthe work plane. Te two are calculateddifferently and are not interchangeable. Allelse being equal, a fixture in a room with a

low RCR will have a higher coefficient ofutilization than if it were in a room witha high RCR. CU values are given by thefixture manufacturer.

able 4 shows how rapidly the CUvalue drops as wall reflectance decreasesor as RCR increases.

Table 4: Typical Coefficient of

Utilization (CU) Values

Reflectance

(Wall)50 30 10

Reflectance

(Ceiling)80 50 80 50 80 50

1 67 56 65 53 53 51

2 66 54 63 51 51 49

3 65 52 61 50 50 48

4 64 50 59 48 48 46

5 63 48 57 46 46 44

6 61 46 53 44 44 42

7 59 43 51 42 42 40

8 56 41 49 40 40 38

9 54 40 47 38 38 36

10 51 39 45 36 36 34

Light Loss Factor: Light distributionis not only affected by the color andreflectance of room surfaces andfurnishings but also by change inlighting output over time, which isprincipally a function of lamp lumendepreciation and fixture dirt buildup.Lumen depreciation data can be foundin technical information suppliedby the lamp manufacturer, and dirt

depreciation values can be taken fromgraphs (IESNA) for various types offixtures and dirt environments.

Once these Light Loss Factors have beentaken into account, one has a more realisticpicture of the “maintained foot-candlelevel.” Te number of lamps (or fixtures)needed to attain that sustained minimumlight level over a lamp’s lifetime can thenbe determined by the zonal cavity formula:

Tis method is heavily dependent onseveral assumptions: that surface reluctancesare reasonably accurate, the fixtures are

L=20ft

Fixture hangs below

ceiling 1.5ft H-6 ft

Task height=2.5 ft

Desk

Desk

W=10ft

ig 10: Example for Room Dimensions,

lacement of Lighting Fixture, and RCR

alculation

Source: E Source Lighting Atlas)

10ft

140

120

100

80

60

40

20

0

100 200 300 400 500 600 700 800 900 1000

S y s t e m E ffi

c a c y ( L u m e n s / W a t t )

System watts

High Pressure Sodium

Metal Halides

System Efficiency < 60 lm/W not allowed per ECBC unless controlled by a mo-

tion sensor

Fluorescent

Incandescent

Fig 9: Exterior Grounds Lighting and specific Technologies

(Source: Adapted from ASHRAE/ IESNA Standard 90.1-1999)

R o o m C

C a v i t y R a t i o ( R C R )



10/12

reflectance. Avoid furniture colors andplacement that will interfere with lightdistribution. Keep ceilings and walls asbright as possible.

Avoid glareInability to control glare is the mostcommon failure in incorporatingdaylighting and especially important

where computer use is extensive. Bestpractice gla re control includes the use ofadjustable blinds, interior light shelves,fixed translucent exterior shadingdevices, interior and exterior fins, andlouvers.

Control Daylight strategies do not save energy

unless electric lights are turned offor dimmed appropriately. ECBCrequires controls in daylit areas thatare capable of reducing the light outputfrom luminaire s by at least half. It isimportant to have properly functioningcontrols that are placed in appropriatelocations and are calibrated to providea consistent level of lighting. Goodlighting design is critical for an energy-efficient and comfortable building.• Install effective placards at lighting

controls;• Install dimmers to take advantage of

daylighting and where cost-effective;• Replace rheostat dimmers with efficient

electronic dimmers;• Combine time switching with

daylighting using astronomicaltimeclocks;

• Control exterior lighting withphotocontrols where lighting can beturned off after a fixed interval.

Design Tips

Many offices that were designed tohandle typing and similar horizontaloffice tasks earlier are now filled with

evenly distributed in the room; and otherconcerns such as voltage, room temperature,fixture temperature, and ballast factor arenormal and will not affect lamp lumenoutput. Te basic RCR calculation assumesthat the fixtures are mounted on the ceiling;variations in the RCR calculation methodcan account for direct/indirect fixtures

mounted on pendants.Te above discussion pertains to casesinvolving uniform light levels. In somecases, non-uniform levels are better, even ifexisting levels are uniform. Tis typicallyoccurs in merchandising, where one would

want products to stand out.

Tips for Energy Efficient

Lighting

Any lighting system generates heat thatneeds to be dissipated . By designing anenergy efficient lighting system that in-tegrates daylighting and good controls,heat gains can be reduced significantly.his can reduce the size of the HVACsystem resulting in first-cost savings.

Daylighting Tips

Daylighting benefits go beyond energysavings and power reduction. Daylightspaces have been shown to improve people’sability to perform visual tasks, increase

productivity and reduce absenteeismand illness. Building fenestration shouldbe designed to optimize daylighting andreduce the need for electric lighting.Following tips can help in designing anintegrated lighting system:

Coordinate with design of electriclights;• Plan the layout of interior spaces—

use the layout to allow daylight topenetrate far into the building (Fig.

11).• Orient the building to minimize

building exposure to the ea st and westand maximize glazing on the southand north exposures.

• Follow ECBC Visible Lightransmittance (VL) requirements[ECBC 4.3.3.1] for windows—tomaximize light and visual quality.

Effective daylighting strategy shouldinclude a combination of the following:

Address interior color schemes;

Interior surfaces, and especiallythe ceiling, must be light colored.Consider light colored furniture androom partitions to optimize light

desktop computers and workstations(often having reflective surfaces), whichrequire careful consideration of bothhorizontal and vertical illumination inthe offices.• Deal with each activity area and each

fixture individually;• Eliminate excessive lighting by reducing

the total lamp wattage in each activityarea;• Lighting layout should use task lighting

principle. Install focussing lamps orflexible extensions wherever needed;

• Plan for future changes in activitiesand space layout. Install fixtures andcombinations of fixtures that provideefficient lighting for all modes of spaceusage.

• While selecting recessed lightingfixtures, one must evaluate the reductionin lamp life as a result of higher junctiontemperature (Fig. 12).

Simulation Tips in Lighting DesignSimulation using a variety of computersoftware tools is not only the way adesign professional or team determinescompliance with the ECBC, but itmay be the best method for guiding adesign using a system-based approach.Lighting software helps users comparelighting alternatives and make sure thatthe ultimate design choice will provide

quality light. A wide range of variables—different light sources, fixtures of varyingefficiency and photometric, daylighting,and rooms with a wide range ofgeometries and surface finishes—allmake lighting design a challenge worthyof computer modeling.

In order to be useful, the mostsophisticated software tools requiretraining and experience on the part of theuser, but numerous simpler programs arealso available for the designer who doesnot need all the functionality of the most

complex products. A number of lightingsoftware tools are also available free ofcharge. Tey come from governmentagencies and private companies, and they

Top Li ghti ng

Clear acrylic

glazing

Light Shelf

Side Lighting

White translucent acrylic glazing

he schematic shows a mix o top-lighting , side-lighting, light shelves, high re lectance ceilings and

wal l di usio n to p rovi de a irl y un ior m dee p-pl andaylighting without the glare o direct sunlight.

Fig 11: Simple daylighting Techniques


R2=0.96

T- point Temperature (deg c)

50000

40000

30000

20000

10000

0

35 40 45 50 55 60

L i f e ( h r s )

ig 12: Effect of Junction Temperature

n Life of LED Lamp

Source: Lighting Research Institute)



11/12

• Replace ballasts with high efficiencyor reduced wattage types, or upgradeballasts and lamp together;

• Relocate or reorient fixtures to improvevisual quality;

• Modify existing fixtures to reduce/eliminate light trapping and/or improvelight distribution. In fixtures having

shades that absorbs light, modify oreliminate the shade;

able 5 provides an overview oflighting design tools used by the lightingprofessionals.

Lighting Retrofit Tips• Replace incandescent and other

inefficient lamps with lamps withhigher lighting efficacy;

•

Eliminate excessive lighting; disconnectthe ballast or remove the fixture wherethey are not needed;

offer a wide range of capabilities. Moreinformation about lighting softwareis available from the Building EnergySoftware ools Directory maintainedon the U.S. Department of Energy

Web site. In addition, Te IlluminatingEngineering Society of North Americaperiodically conducts a survey of lighting

software tools and publishes the resultsin its magazine Lighting Design and Application (LD+A).

Table 5: Commonly Used Lighting Design Software

Software Discription Contact Information

AGI32Lighting calculation and visualization program. Latest release, 1.7, addsdaylight factor calculations, unified glare-rating calculations for discomfortglare in interiors. Company also offers a simplified version, AGI-Light.

Lighting Analysts Inc. Littleton,Colorado, USA Phone: +1-303-972-8852E-mail: [email protected]: www.lightinganalystsinc.com

Autodesk VIZ Tree-dimensional modeling, rendering, and presentationcapabilities. Includes daylighting calculations.

Autodesk Inc.San Rafael, California, USA Phone: +1-800-440-4198URL: www.autodesk.com

Building Design Advisor

A data manager and process controller that allows building designers touse several analysis and visualization tools throughout the building designprocess. Te current version includes links to a simplified DaylightingComputation Module (DCM), a simplified Electric lighting ComputationModule (ECM), and the DOE-2.1E Building Energy Simulation software.

Konstantinos PapamichaelLawrence Berkeley NationalLaboratory Berkeley, California Phone: +1-510-486-6854E-mail: [email protected] URL: http://gaia.lbl.gov/

DAYSIM

Daylighting analysis software that predicts the annual daylight availabilityand electric lighting use in buildings that use manual and automated lightingand blind controls. Based on Radiance software and available for free.

Christoph ReinhartNational Research Council Canada Institute for Research in ConstructionOttawa, Ontario Canada Phone: +1-613-993-9703E-mail [email protected] URL: www.daysim.com

DIALux Lighting calculations and modeling from DIAL, a Europeanlighting services organization that is supported by manufacturers.Useful for simple calculations and available for free.

DIAL GmbH

Lüdenscheid Germany Phone: +49-0-2351-10-64-360E-mail: [email protected]: www.dial.de

LIE-PROLightin g design tool from Hubbell Lighting Co. Includesindoor and outdoor lighting capabilities and rendering.

Columbia Lighting, Spokane, Washington, USA Phone: +1-509-924-7000E-mail [email protected]: www.columbialighting.com/litepro/features.htm

Lumen Designer

Te latest upgrade of the popular Lumen Micro product. Adds internalmodeling and daylighting capabilities. A highly interactive interfacefeatures a Design Wizard for setting up complex projects. Productalso includes plug-ins for roadway lighting and advanced rendering.Company offers a simplified version: Simply Lighting 2002.

Lighting echnologies Inc.Denver, Colorado, USA Phone: +1-720-891-0030URL: www.lighting-technologies.com

ProjectKalc

Helps the user compare the energy and operating cost impacts of alternativelighting upgrade solutions. It can handle lighting upgrades involving controls,relamping, delamping, tandem wiring, and more. It includes user-modifiabledatabases of costs, labor time, and performance for over 8,000 commonhardware applications. Te software is available free of charge through theU.S. Environmental Protection Agency (EPA) Energy Star program.

EPA Energy Star Program, Washington, D.C., USA URL: www.energystar.gov/index.cfm?c=business.bus_projectkalc

Radiance

An advanced lighting simulation and rendering package that calculatesspectral radiance values and spectral irradiance for interior and exterior spacesconsidering electric lighting, daylight, and inter reflection. Used by architectsand designers to predict illumination, visual quality, and appearance ofdesign spaces. Used by researchers to evaluate new lighting and daylightingtechnologies and study visual comfort and similar qualities related to the visualenvironment. It is available for free. Tere is a project underway to develop anice interface to this extremely powerful application to improve its usability.

Charles EhrlichLawrence Berkeley National LaboratoryBerkeley, California, USA Phone: 510-486-7916E-mail: [email protected] URL: http://radsite.lbl.gov/radiance/HOME.htmlFree

Visual Lighting analysis software for interior and exterior applications. Integratesanadvanced 3-D modeling environment with an intuitive interface. Professionalpresentation capabilities enable user to quickly develop, analyze, and modifyadvanced lighting designs. Basic version is available free of charge.

Acuity Brands Lighting Visual Support Center, Conyers, Georgia, USA Phone: 800-279-8043E-mai: [email protected]: www.visuallightsoftware.com



12/12

Developed by USAID ECO-III Project eam:

echnical Contents: Satish Kumar, Ravi Kapoor,

and Anurag Bajpai

Editing: Ravi Kapoor

Layout Design: Meetu Sharma

For more information:

Dr. Ajay Mathur, BEE ([email protected])

Dr. Archana Walia, USAID ([email protected])

Mr. Aalok Deshmukh, ECO-III Project([email protected])


the less likely it is that sensors will bedisabled, disconnected, or bypassed.he following provides a strategy forselecting the right controls for buildings.

Define Application Goalshe first step in determining the rightcontrol strategy is to thoroughly define

and understand the application goals.Lighting designers should be asked toprovide iso-lux charts which discuss theillumination level in the space (Fig. 13).

Switching or Dimming he first primary decision after definingthe load and the application goals is

whether to switch or dim the load.Switching and dimming are stand-alone strategies but are often used inthe same facility, and may be integratedin the same control system. Dimmingcapability should always be incorporatedinto areas where daylighting is theprimary lighting approach. When usingphoto sensors in a dimming strategy,it is important to properly commissionand calibrate it. Failure to do so cansometimes result in more energy use.

Degree of Automation Needed It is worthwhile to determine theamount of local vs. centra l control that isneeded from the lighting control system.

Manual lighting controls range from asingle switch to a bank of switches anddimmers that are actuated by toggles,rotary knobs, push buttons, remotecontrol, and other means. Manual

controls can be cost-effective optionsfor small-scale situations. However, asthe lighting system grows, automatedsystems become more cost-effective andare better at controlling light . Manualcontrols often waste energy becausethe decision to shut off the lights whenthey are not needed is based entirely on

human initiative.

References:

Book References:1. E Source (2005): E Source echnology

Atlas Series - Volume I: Lighting,Boulder, CO, USA

2. Energy Efficiency Manual, by DonaldR. Wulfingoff, Energy Institute Press.

3. Energy Conservation Building Code,Ministry of Power, May 2007.

Web References:1. Illuminating Engineering Society of

North America (IESNA),http://ww.iesna.org

2. Advanced Buildings: echnologiesand Practices,http://www.advancedbuildings.org/

3. he Lighting Research Center atRensselaer Polytechnic Institute,http://www.lrc.rpi.edu/

4. Heshong-Ma one Grouphttp://www.h-m-g.com/

5. he New Buildings Institute,

http://www.newbuildings.org/light-ing.htm

6. Windows and Daylighting , LawrenceBerkeley National Laboratory,http://windows.lbl.gov/

Maintenance TipsTere are important considerations thatneed to be made to optimize a design forenergy efficiency in lighting: reductionin first costs, reduced operation andmaintenance, and increased occupantproductivity and comfort. Consider thefollowing:•

Good lighting also effects the operationand maintenance of a building. Asimpler and easy to control lightingsystem will lower the “first cost” of thesystem.

• Fluorescent lamps last an average of10 times longer than incandescent andreduce re-lamping labor costs.

• Clean fixtures and lamps at appropriateintervals to maintain optimum lightingoutput.

Lighting Controls TipsPurpose of Lighting Controls: In manyapplications, the overall purpose of thelighting control system is to eliminate

waste while providing a product ivevisual environment. his may entail:1. providing the right amount of light;2. providing light where it’s needed.

A few issues to keep in mind whi ledesigning controls are:• Install a separate control circuit for

each lighting element that operates on a

distinct schedule;• Where light fixtures are needed in a

predictable variety of patterns, installprogrammable switches;

• Install lighting controls at visible,accessible locations;

• Where lighting is needed on a repetitiveschedule, use timeclock control;

• Install occupancy sensors in bathrooms,conference rooms, and other spaces notin constant use.

Controls, switches, shades, timers,and other lighting strategies canget complicated. It is likely thatadjustments will occur after occupancy.he easier the lighting system is tounderstand and adjust to accommodatethe occupants and building function,

Align control circuits parallel to daylight

contours when daylight levels vary across the

space. In these plans and section o a sidelit

oice and skylit actor y, “A” experiences the

most daylight and is turned o or dimmed

irst, “B” is controlled second, “C” receives

the least daylight and is let at ull power tomaintain wal l brightness. he oice pendent

direct-indirect luminaires are dimmed in

response to daylight.

B C C

C

B

A

B

A

C

A

800Lux 600Lux 400Lux 200Lux

Fig. 13: Plan Views of Daylight Isolux Contours

(Source: Adapted from Advanced Lighting Guidelines, New Buildings Institute)

lighting tip sheet (v-2.0 march 2011)

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